Question

How does ammonium hydroxide helps in distinguishing between :-
i) Lead hydroxide and zinc hydroxide
ii) Lead nitrate and zinc nitrate ?

Answer 1

Hi there!

Ammonium hydroxide helps in following way :

i. Zinc hydroxide is soluble in excess ammonium hydroxide and gives a colourless solution whereas lead hydroxide is not soluble in excess ammonium hydroxide.

$Zn(OH)_{2}$ + $4NH_{4}OH$ → $4H_{2}O$ + $[Zn(NH_{3})_{4}](OH)_{2}$

ii. Zinc nitrate gives white ppt. which dissolves in excess ammonium hydroxide and produce a colorless solution whereas lead nitrate gives a chalky white ppt. of lead hydroxide which doesnot dissolve.

$Pb(NO_{3})_{2}$ + $2NH_{4}OH$ → $2NH_{4}NO_{3}$ + $Pb(OH)_{2}$

[ Thank you! for asking the question. ]
Hope it helps!